In semiconductor manufacturing, the accuracy of the stepping of a reticle mask for photolithography exposures is very important. It is crucial that during each stepping action, the stepper equipment moves the reticle a precise predetermined distance in both the x and y directions. Minor accuracy errors in the exposures may produce an unusable product, particularly as the critical dimensions of features in the integrated circuits are reduced.
Currently, stepping is manually analyzed for accuracy with the aid of a microscope. The prior art manual method is time consuming because alignment is analyzed during the execution of a test pattern. Also, inaccuracies, such as rotation, may be misanalyzed due to human error.
The present invention is an improved method for insuring stepper alignment.